Exposure apparatuses used in the photolithography process illuminate the center part of a mask using exposure light and expose a work piece using exposure light that has passed through said mask. Masks used in exposure are held on a mask stage of an exposure apparatus. A known technique in holding the mask using the mask stage is, for example, holding the mask on the mask stage on top of a holding member.
As the number of irradiations of exposure light increases, the temperature of the mask that receives irradiation of exposure light increases, and the mask deforms due to thermal expansion, and distortion can occur. When deformation of the shape of the mask occurs, the pattern projected onto the work piece via said mask unfortunately is deformed. In the case in which the mask deforms due to thermal expansion, many linear components are included in the deformation components, so, for example, by performing linear corrections such as varying the magnification of the projection optical system with respect to the pattern projected via said mask, it is possible to correct for the deformation of said mask.
However, in the case in which the mask is held by a holding member, deformation of the mask is partially restricted by said holding member, and a status in which many nonlinear components are included in the mask deformation components occurs. Even if linear correction such as varying the magnification of the projection optical system, for example, were performed with respect to a pattern projected via a mask that contains many nonlinear components and has deformed, reducing deformation of said pattern would be problematic. When the pattern is unfortunately projected onto the work piece in a deformed status, there is a possibility of exposure defects being generated.
Taking circumstances such as the above into account, the purpose of the present invention is to provide an exposure method, a device manufacturing method and a mask that are able to restrict exposure defects.